This invention relates to stair mounted elevators or lifts, commonly known as stairlifts.
A stairlift, in the form of a carriage mounted for movement along a rail, is a well known form of apparatus for moving aged or handicapped persons up and down a staircase. Such a form of apparatus needs to be designed so that the carriage runs smoothly along the rail yet is resistant to forms of movement other than linear movement along the rail. Particular movements which need to be resisted are skewing about the rail, which might cause the carriage to jam as it moves along the rail; tilting of the carriage about an axis transverse of the rail which, unless strictly controlled, can cause the carriage seat to move off the horizontal and alarm a user; and rotation of the carriage about the rail axis which, again, would have an alarming affect on a user.
The desired smoothness of longitudinal movement, as well as resistance to unwanted movement, is typically provided by including within the carriage, spaced pairs of rollers which serve to mount the carriage on the rail. Generally, the greater the distance between the rollers, the more stable the carriage is on the rail. As a consequence rail designs have tended to be quite broad so that the roller spacings can be as wide as possible. This, in turn, has meant that the resulting stairlift has tended to occupy a considerable margin down one edge of a staircase.
Typical prior art stairlifts have at least six pairs of rollers to provide the necessary rolling support to the carriage whilst resisting the undesired movements mentioned above. Obviously the more rollers which are included, the greater the cost. However, even with six roller pairs, some prior art stairlifts still display a degree of uncontrolled movement in the assembly due to the need to provide clearance between opposite sides of the rollers, and the rail.
It is an object of this invention to provide a stairlift which is compact in nature, includes a minimum number of operating parts and feels safe and secure to a user; or to provide a form of stairlift which will at least provide a useful choice.
Accordingly, in one aspect, the invention provides stairlift apparatus including:
tubular rail having a substantially uniform cross-section and a plurality of rolling surfaces extending longitudinally thereof;
carriage mounted for movement along said rail, said carriage being arranged to locate a seat section above said rail and having a plurality of rollers which engage with said rolling surfaces to support said carriage on said rail,
said apparatus being characterised in that said rolling surfaces are arranged about the outer surface of a tubular rail of non-cylindrical cross section and said rollers are arranged to support said carriage for rolling movement along said rail yet prevent said carriage from rotation about said rail.
Preferably the construction and arrangement is such that said rollers and said rail further operate to resist tilting and skewing movement of said carriage with respect to said rail.
Preferably said rail has at least three rolling surfaces arranged about the outer surface of said rail, a roller contacting each of said rolling surfaces. More preferably said rail includes four rolling surfaces arranged about said cross-section to extend longitudinally of said rail, a pair of longitudinally spaced rollers being provided for each of said rolling surfaces.
Said rolling surfaces are conveniently provided as an upper pair and as a lower pair and said rail preferably further includes rail mounting means defined between said lower pair of rolling surfaces.
The individual rolling surfaces of each pair, and the juxtaposed surfaces of the different pairs, are preferably perpendicular to each other and drive transfer means is preferably provided on or adjacent one of said rolling surfaces. The drive transfer means is preferably provided on one of the upper rolling surfaces.
Whilst the drive transfer means could comprise a section of the rail adapted for frictional engagement with the carriage, said drive transfer means preferably comprises a gear rack.
The apparatus as set forth above may further including rack cover means to at least partially overlie said rack and screen said rack from sight when the rail is viewed from above. This rack cover means preferably comprises a moulding or extrusion fixed above the rack and extending longitudinally of the rail.
The apparatus may further include a drive wheel mounted within said carriage, the periphery of said drive wheel being engageable with said drive transfer means so that, upon rotation of said drive wheel, said carriage is moved longitudinally of said rail; and drive means mounted within said carriage, said drive means having a drive shaft rotatable about a drive axis, said drive wheel being mounted for rotation on said drive shaft; the arrangement being characterised in that said drive means does not overlie said rail when viewed in a direction perpendicular to said drive axis. In such an arrangement, the drive transfer means preferably comprises a rack and said drive wheel comprises a pinion which, in use, engages with said rack.
Preferably all of said rollers which support the carriage on the rail are identical and the mounting arrangement of the rollers is preferably such that each of said rollers is only loaded substantially perpendicular to its respective axis of rotation.
The carriage preferably includes a pair of spaced side plates which extend down to at least partially overlie opposite side parts of said rail, said rollers extending from said side plates. These side plates preferably comprise outer surface parts of said carriage and may include bracing means on the inner surfaces thereof, said plurality of rollers being mounted on said bracing means.
Said side plates and said bracing means are preferably press formed from sheet metal and subsequently welded together.
In order to allow for adjustment of said carriage on said rail, said rollers are preferably provided in co-operating pairs, wherein some of said rollers of each pair rotate about fixed axes whilst the axes of the remainder of said rollers in each pair may be displaced in directions perpendicular to said axes.
In a further aspect the invention provides a stairlift rail having a substantially uniform tubular cross-section and a plurality of rolling surfaces extending longitudinally thereof, the rail being characterised in that said cross section is non-circular and said rolling surfaces are arranged about said cross-section on the outer surface of said rail.
The rail as set forth above preferably further includes a drive surface co-planar with, or parallel to, one of said rolling surfaces, and a rail mounting plane, wherein said drive surface is arranged at substantially 45xc2x0 to said rail mounting plane.
Preferably said drive surface is constructed and arranged to mount a drive rack.
The rail preferably further includes locating means to receive and locate joining members, said joining members being operable to join like sections of rail together in end-abutting register. Such locating means preferably include a plurality of joining channels formed on the inner surface of said rail, said channels, in use, receiving joining members in the form of pins.
Said rolling surfaces are preferably provided as a lower pair and an upper pair, each of the surfaces of the upper pair being juxtaposed to a surface of the lower pair but having an apex therebetween and wherein a joining channel is formed at or adjacent to the inner surface of each apex.
Said joining channels are preferably substantially circular in section so as to receive, by way of interference fit, joining pins of circular section.
A stairlift rail in accordance with the invention is conveniently formed as an aluminum extrusion.
In still a further aspect the invention provides a stairlift rail for use in the apparatus hereinbefore set forth.
Many variations in the way the present invention may be performed will present themselves to those skilled in the art. The description which follows is intended as an illustration only and the absence of description of particular alternatives or variants should in no way be applied to limit the scope of the invention. Such description of specific elements which follows should also be interpreted as including equivalents whether existing now or in the future. The scope of the invention should be defined solely by the appended claims.